<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <div class="aspect"></div>
  </body>
  <style>
    .aspect {
      width: 50%;
      aspect-ratio: 16/9;
      background-color: aqua;
    }
  </style>
</html>
